1. Field of the Invention
The invention relates to an improved process for preparation and reduction of .alpha.,.beta.-unsaturated nitriles.
2. Description of the Prior Art
Bull. Soc. Chim. France 1963, pp. 677-681 shows that .beta.,.beta.-dimethyl-.alpha.-cyanostyrene can be prepared in 30% yield by refluxing 0.3 mol of benzyl cyanide, 1.3 mol of acetone and 10 ml 3 N methanolic KOH for two hours, followed by cooling, neutralizing, drying and distilling. This publication also shows that .beta.-methyl-.alpha.-cyanostyrene is obtained in 47% yield by heating 0.25 mol of benzyl cyanide, 1 mol of acetaldehyde and 2 ml 3 N methanolic KOH until the mixture becomes cloudy (about 65.degree. C.), followed by cooling, neutralizing, drying and distilling. Applicant has found that further stirring under reflux does not increase these low yields. The molar ratios of KOH to benzyl cyanide in these two experiments were 0.10 and 0.024, respectively.
J. Org. Chem. 40 (1975) 127-128 shows that alpha, beta-ethylenically unsaturated nitriles can be hydrogenated to give a high yield of the corresponding saturated nitriles by reaction with methanol and magnesium, followed by acidification of the reaction mixture obtained. In a typical experimental procedure a starting amount of the unsaturated nitrile of 0.1 mol/l methanol was used. The use of such highly dilute solutions is not very attractive for a commercial process. Applicant has tried to use more concentrated solutions but has found that in such a case the reaction with methanol and magnesium comes to a standstill at a moment when a considerable part of the alpha,beta-ethylenically unsaturated nitrile is still unconverted.
It has now been found that an increase in the molar ratio of KOH to benzyl cyanide considerably enhances the yield of .alpha.,.beta.-unsaturated nitriles and that the presence of certain salts promotes their hydrogenation.